Fluid pressure operated jack



Jan. 24, 1939. s, M. PARKER 2,144,893

FLUID PRESSURE OPERATED JACKv INVENTOR.

Jan. 24, 1939. s. M. PARKER 2,144,893

FLUID PRESSURE OPERATED JACK Filed May 1'7, 1958 3 Sheets-Sheet 2 Syd/rey MacDo/m/af /Zrer y ///74] A 7' TOP/VEK Jan. 24, 193.9. 5, M. PARKER 2,144,893

FLUID PRESSURE OPERATED JACK Filed May 17, 1938 3 Sheets-Sheet .'5

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' SydnyMacDo/za/o/ Par/er Patented Jan. 24, 1939 UNITED STATES PATENT OFFICE FLUID PRESSURE OPERATED JACK Application May 17, 1938, Serial No. 208,474 In Great Britain November 11, 1936 3 Claims.

The invention relates to fluid pressure actuated jacks, adapted to be used for operating re-v tractable undercarriages, bomb release gear of aircraft and the like, and provided with locking mechanism acting to retain the jack in either or both of its extreme positions. y

An object of the invention is to provide a system which will prevent any one of a series of such fluid pressure actuated jacks from operating until all of the series are unlocked. The risk of distorting or jamming the undercarriage in the event of one of the locking means being stiffer than the. other of others, is thus avoided.

In the system herein disclosed the lock controlling means is embodied in a fluid actuated system comprising onel or more pairs of jacks to be operated in unison from a common source of fluid pressure, each fitted with locking means released by the said pressure, and including a change-over valve device actuated by the respective locking means to prevent any jack from being operated until all locking means are released, each of said change-over valve ydevices having a main pipe connection fed with pressure uid from the source and being adapted to lead fluid from this main connection to the corresponding lockreleasing means when the locking means is in action, or to the working space of another jack when the said locking means is released.

Other objects and features of the invention and other novel combinations of parts and desii-able particular constructions will be apparent from the following description and from the accompanying drawings, in which Figure 1 is a diagram indicating a general arrangement that may be used in applying the present invention to a single set of jacks having fluid actuated locking devices; Y

Figure 2 is a diagram indicating a general arrangement used for inter-connecting two sets of jacks having fluid actuated locking devices; and Figure 3 is a diagram showing a method of interlocking three jacks.

In the example shown in Figure 1 a pair of jack units Ill and II, such for example as are commonly employed for operating a retractable aircraft undercarriage, are arranged side by side, and have plunger members I2 and I3 respectively adapted to be forced down by fluid pressure introduced through pipe connections I4 and I6 in order to extend the jack and to move upwardly by passing fluid under pressure through the connections I6 and I1 when the jack is required to be contracted or shortened.

In order that the Jacks may be positively held in their fully closed condition each of the plungers I2 and I3 is formed with a flange I8 which is adapted to be engaged by the turned in extremities I9 of a pair of locking levers 20, these being pivoted upon lugs 2| as indicated at 22. 5 At its upper endeach of the levers 20 is formed with a slot 23, and these are connected by a sliding pin 24 with a rod 25 secured to a piston 26 disposed within a hydraulic cylinder 21. A spring 28 normally urges the piston 26 in an l0 upward direction and consequently causes the levers 20 to lock the plunger I2 mechanically when it is disposed in its uppermost position.

The cylinder 21 is extended to form the casingof a valve vdevice 29 having a xed seating 15 36, which is engaged by the head 3| of a mushroom valve element when the piston 26 is moved to its lowermost position during the process of releasing the locking levers 20, the stem 32 of said valve element being adapted to engage the 20 piston 26. The valve element 3|, 32 is hollow and is arranged to accommodate slidably the stem 33 of a second mushroom valve element having a head portion 34 adapted to engage a fixed seating 35 by the action of a coiled com- 25 pression spring 36 tending to force apart the two heads 3l and 34. -A further coiled compression spring 31 acts between the head 3| and the end of the casing 29 so as to keep the stem 32 in firm contact with the piston 26. The movement 30 of the stem 33 within the valve element 3|, 32 is limited by a pin 38 which is secured to the head 3| and passes through a slot 39 in the stem 33. As the piston 26 is moved downwardly by pressure fluid, as will be hereinafter explained, 35 the spring 31 causes the valve element 3|, 32 to follow, while the spring 36 firmly holds the head l34 of the second valve element in contact with the seating 35. Just before the head 3| reaches the fixed seating 30, however, the pin 38 contacts 40 with the lower end of the slot 39, and thus the final movement of the valve element 3|, 32 closes the seating 30 and at the same time causes the head 34 to leave the seating 35. A valve device of identical construction is fitted to the jack II 45 and is indicated generally at 29a.

The system as a whole is a double-acting one and is supplied with fluid under pressure to a pipe connection 40 in order to unlock and lower the two plungers I2 and I3 while pressure fluid 50 fed into the opposite pipe connection 4| correspondingly raises the plungers I2 and I3 until they automatically become locked, a sloping surface 42 on each plunger being arranged to slide past oblique surfaces 43 on the locking levers 20 55 until such time as the latter are free to move inwardly and hold the plunger in a locked condition. The action of the valve devices 23, 29a in accordance with the invention is as` follows. When pressure fluid is fed into the connection 40 it passes into spaces Il and a in the respective valve devices by way of main connections I5 and "a, Both jacks being locked, the valve elements are in the positions shown in Figure 1, and therefore the fluid passes through the valve seatings 3B, 30a and presses downwardly the two pistons 26 and 26a, thus moving outwardly the lower ends I9 of the locking levers 20. At the moment when the plungers I2 and I3 are free the heads 3| and 3Ia reach the fixed seatings 3l and 30a so that the supply of uid from the main connection 45 is transferred past the seating 35 to a pipe I8 which leads to the jack connection I5, thus enabling said fluid to extend the jack II. Similarly the uid fed -through the main connection a passes through a pipe connection 46a and has the effect of extending the jack III. In the event of say the jack I0 becomi-ng unlocked prior to the jack II it will be seen that the iiuid from the main connection 45 is transferred by the opening of the valve seating 3B to a pipe 41a which enables the pressure uidV from the valve d evice 29 to act upon the piston 28a until' such time as this piston has completed its movement. At the same time pressure iluid is fed to the connection II, but, of course, it cannot eil'ect the extension of the Jack Il until the corresponding locking means have been released. Thus, the two valve devices 29, 29a act as changeover valves, and each feeds either the corresponding locking means or else the other jack according to the position occupied by the valve elements.

A s shown in Figure 2 the jacks are associated in pairs and are indicated at III, II and Na, IIa, the input of pressure fluid from a pipe connection 6I to the unlocking means of the jacksl and II being controlled by an auxiliary valve device indicated at 60, while a similar valve device Sa is associated with the two jacks Ila and IIa. The locking means of the four jacks comprise pairs of levers 20 adapted to hold the plunger members I2, I3 and I2a, I3a in their fully raised positions, said levers 20 being actuated by valve devices 32, 63 and 62a, 33a, all identical in construction. For actuating the auxiliary valve devices 30 and 60a however, transverse links 64, a are carried by the stems 2l and 25a respectively and are connected at their middle points with push rods 65, 85a. 'I'he lower end of each of these rods acts through a lever 1I, 1Ia and serves to raise a push rod 12, 12a passing slidably through the casing of the corresponding auxiliary valve GU or 60a. and each is thus arranged to operate a corresponding pair of valve members indicated at 36, 3! and lla. 69a respectively. The stems of these valve members are telescopically slidable and are interconnected by pin and slot devices 13, 13a, while springs 10 and 10a serve to move the valve members G3, a upwards into contact with the push rods 12, 12a.. A further spring 1l, 14a in each auxiliary valve tends to hold the valve member 69, 69a upon its seating but the slot of the pinand-slot device 13, 13a is of such length that the valve member 69, 69a is moved on.' its seating just as the corresponding valve member $3-, 36a' is engaged with its seating 63, 83a during the upward movement of the push rod 12, 12a. Thus when pressure fluid is fed through the connection 3| itis allowed to pass to the connection Il feeding the valve devices 32 and 33 of the Jacks Il and II, while the fact that the head of the valve member a is ci! its seating a enables the pressure fluid similarly to reach the pipe connection a feeding the valve devices 62a and 33a ofthe Jacks Ila and Ila respectively. The action in each pair of Jacks is such that the release of both locking means of any one pairl Vof jacks causes the centre part of the corresponding link 34 or a to be moved downwardly suilicient to close the valve seating 63 or "a and open the corresponding passage past the head of the valve member l! or 33a in the auxiliary valves. Assuming that the two jacks I0 and II become unlocked before the jacks Ita-and IIa this will mean that the supply of fluid through the pipe connection ll is cut off and the feed through the pipe II therefore passes through a connection 3| leading to the 'connection lla, which latter it will be seen is already connected with the supply 0I by way of the valve seating 33a. Thus, the whole of the duid pressure is concentrated upon unlocking the jacks Ia and IIa, and when this has lbeen effected the consequent lowering of the centre part of the link a allows the valve seating Ila' to be closed and the valve member 89a to be opened. This action enables fluid from the pipe connection II to pass the valve member 33a and thus reach the pipe connection 40, from which latter it flows into the valve devices I2 and I3 and thence to the cylinder connections I4' and II. since the unlocking of the plungers I2 and I3 has already opened the-valve seating 3l in the manner previously explained. The Jacks .illustrated are doubleacting ones, and the fluid pressure used for closing or shortening them is supplied through a connection 4I having branches connected to the respective cylinders at II, I1, lia and Ha` It will be noted that push rod 12, although normally abutting valve I8, is not actually integrated therewith; and that the closing of the valve 33, as well as the subsequent holding of said valve in the closed position, is due to the expansive force of spring 1I, and is therefore independent of the exact position of the push rod 12, once said push rod has been withdrawn upwardly in response to release of locks 2l. Hence any slight inaccuracy in the lock actuating linkage, or any subsequent lossI of pressure thereupon, will not interfere with the continued, independent, maintenance of valve I3 in the firmly seated position, pending return of the locks to the locking position. 'Ihe foregoing applies correspondingly to valve lla, of course.

- Various modifications may. of course, be made in the arrangements described, and the principle shown in Figure v1 may be extended to embrace any number of jacks operated from a common source of pressure fluid. Thus, as shown in Figure 2 the same general method can be used for interlocking threeiacks. The middle and left hand Jacks are identical with the Jacks Il and II shown in Figure 1, and are provided with an auxiliary valve 3l as before. The third Jack, indicated at IIb is provided with a valve device .2b which is identical with the valve devices l2 and 33 but is connected so as to function similarly to the previous auxiliary valve Ma. Thus,

if the jack IIb is the nrst to become unlocked,

the valve seating 33h is automatically closed, and the supply of fluid from the conduit II is diverted to the valve devices of the jacks Il and II by way ofthe conduit "b, and it is not until muses the auxiliary valve ll is actuated by the unlocking of both these jacks Il and Il. that the supply of iiuid can pass through the conduit Il and reach the working space of the jack Nb to extend its plunger IIb. In cases where the jack is locked in its completely extended position the same general arrangements can be used, except, oi course, that the pipe connections il and il to the jack cylinders would be interchanged with the connections- I l andv i1 respectively, suitable modiilcation being made in the mechanical details oi the locking mechanism. In some cases it may be desirable for the plungers to be locked at each extreme position, and for this purpose the interlocking valve systems shown can be duplicated.

Although this invention has been described in connection with certain specific embodiments, the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, theretore, to be limited only as indicated by the scope of the appended claims.

This application is a continuation in part oi iliy3 application No. 173,928 iiled November 10,

What is claimed is:-

1. A fluid operated system including a plurality ot jacks and a locking means for each jack, means for releasing the locking means by pressure iiuid fed to the Jack, a valve device associated with each pair oi.' said jacks for arresting the ilow of fluid to one pair oi Jacks when both locking means therefor have been released, and for leading said uid to another pair of jacks, resilient means associated with each valve device for holding the same in position to arrest ilow to the associated pair oi jacks andv jack releasing means, said resilient means being operative upon release o! the associated locking means, means abutting each valve device prior to release of the locking means to physically bar movement thereof to the ilow arresting position,

lock operating means for withdrawing said abutting means beyond the limit of expansion of said resilient means, so that the latter becomes operativeto hold the associated valve device in said ilow arresting position without further opposition from said abutting means, and independently of the exact position of the locking means, pending return of the locking means to locking position.

2. A iiuid operated system including a plurality of Jacks and a locking means for each Jack, means for releasing the locking means by pressure iluid ted to the jack, and a valve device associated with each pair oi said jacks for arresting the ilow of iluid to one pair of jacks when both locking means therefor have been released, and for diverting said fluid to another pair of Jacks, each oi' said valve devices having relatively movable sections connected by lin and slot connections and having resilient means nor.

mally urging said sections to the above described flow arresting and ilow diverting positions, respectively. v

3'. A fluid operated system includingy a plurality of jacks and a locking means for each Jack, means for releasing the locking`means by pressure fluid fed to one pair oi Jacks, and a valve device associated with each pair ot said Jacks for arresting the iiow o! uidto one pair of jacks when both locking means therefor have been released, and for diverting said iluid to another palr o! Jacks, each oi said valve devices having relatively movable sections and including means to hold the relatively movable sections in the above described iiow arresting and tlow diverting positions, respectively.

SYDNEY- MACDONALD PARKER. 

